Resilient reservoir assembly

ABSTRACT

An inflatable retention catheter&#39;&#39;s resilient inflated reservoir retaining a fluid under pressure is enclosed by a jacket which reduces fluid loss through the reservoir wall during storage and does not inhibit deflation of the reservoir.

United States Patent Inventor Appl. No.

Filed Patented Assignee Jay Z. Balin Des Plaines, Ill. 852,974

Aug. 18, 1969 Aug. 17, 197 1 The Kendall Company Boston, Mass.Continuation of application Ser. No. 508,673, Nov. 19, 1965, nowabandoned.

RESILIENT RESERVOIR ASSEMBLY 6 Claims, 5 Drawing Figs.

U.S. Cl

[51] lnt.Cl ..A6lm 25/00 [50] Field of Search..... 128/348, 351, 246,325,344

[5 6] References Cited UNITED STATES PATENTS 3,378,011 4/1968 Vitello128/349 3,379,197 4/1968 Hayes 128/349 Primary Examiner Dalton L.Truluck Attorney- Robert D. Chodera ABSTRACTt An inflatable retentioncatheters resilient inflated reservoir retaining a fluid under pressureis enclosed by a jacket which reduces fluid loss through the reservoirwall during storage and does not inhibit deflation of the reservoir.

' RESILIENT RESERVOIR ASSEMBLY This application is a continuation ofSer. No. 508,673 filed Nov. 19, I965 and now abandoned.

This invention relates to self-inflating catheters, that is, tocatheters which have a fluid distended elastic reservoir which uponrelease of the contained fluid exerts sufficient pressure whiledeflating to inflate an inflatable retention bulb or balloon near thedistal end of the catheter. More specifically, this invention relates tomeans for reducing fluid loss from the reservoir through its walls instorage and prior to use.

For purposes of this invention, the distal end of a catheter isconsidered to be that end which is inserted into an animal body whereasthe proximal portion of the catheter is that portion which is intendedto be outside the body.

The reservoir of a self-inflating catheter is preferably kept as smallas possible to eliminate bulkiness but it is kept within sizelimitations for other reasons. The retention bulb of an inflatable bulbindwelling catheter has definite size limitations.

On the one hand, it has to be large enough to retain the distal end ofthe catheter in the bladder when the bulb is inflated after insertion.On the other hand, it should not be so large as to interfere-with theefficiency of the catheter as a drainage device or to cause undueirritation of the bladder.

These size limitations are important when it is considered that theelastic reservoirs in use today have fairly high fluid losses throughtheir walls and the difference in volume between maximum and minimumdesirable inflation of the retention bulb is not very great.

I Attempts have been made in the past to provide self-inflatingcatheters with small reservoirs by coating the distended reservoir withvarious gas and vapor retentive coatings. Unfortunately, however, suchcoatings are comparatively inelastic (and some become more so on aging)when compared with the elastic rubber reservoir and, therefore, must bekept at a thickness considerably less than optimum in order to avoidrestricting reservoir deflation. Furthermore, such coatings may presenta very unattractive appearance when the reservoir is deflated and theirthinness restricts the loss of fluid to the bare minimum necessary forpractical usage. What has been unattainable until this invention hasbeen a self-inflatable catheter whose shelf life has been substantiallyincreased.

It is, the primary object of this invention to provide a cover for theelastic reservoir of a self-inflating catheter which does not inhibitdeflation of the reservoir and which significantly reduces fluid lossfrom the reservoir.

Other objects of the invention will be apparent from the drawings andfrom the specification.

It has been found that a reservoir covering jacket whose walls are ofsufficient thickness to significantly reduce fluid loss is effective inthis respect provided a fluid-retaining seal is maintained between theends of the reservoir and the jacket.

Referring to the figures:

FIG. 1 illustrates a self-inflating catheter with the jacket oftheinvention in place over the inflated reservoir thereof.

FIG. 2 illustrates in detail the jacketed reservoir of FIG. 1 prior toinflation of the latter.

FIG. 3, is-an illustration of the jacketed reservoir of FIG. 2 with thereservoir partially inflated.

FIG. 4 is an illustration of the jacketed reservoir of FIG. 2 with thereservoir fully inflated.

FIG. 5 illustrates the comparative values as fluid retentive jackets ofprolate spheroidal, true spherical and oblate spheroidal jackets.

It has been found that when a tubular elastic reservoir is inflated, ittends to assume a prolate spheroidal form'in the inflated, portionfltwould appear at first glance that a jacket closely following the contourof the inflated reservoir would be the most desirable form for a jacket.But as can be seen from the schematic illustrations in FIG. 5 whenpartial fluid loss occurs, the prolate jacket 30 begins to lose itsfluid-retaining sealfirst, thetrue spherical jacket 31 loses itsfluid-retainingseal next while the oblate jacket 32. is just at thepoint of losing its fluid retaining seals. Thus, while all of thespheroidal shapes are somewhat efiecti've, the oblate jacket wouldprevent excessive loss of fluid for a longer period than either of theother shapes. However, while a spheroidal shape is the preferred shape,the end seals and the distance between them are more important than thejacket shape. For instance, one could utilize a cuboid shape so long asthe fluid-retaining seal areas are present at both ends and the distancebetween them is less than the reservoir length when partially inflated.The jacket obviously should not be substantially greater in volume thanthe volume of the inflated reservoir.

Referring once more to the drawings:

In FIG. I, the self-inflating catheter 10 consists of a tubular maindrainage arm 11 with a connector end 12 and a discharge end 13 connectedby a drainage channel 22. An inflating side arm 14 normally has itsinflating channel 21 closed by a clamp 15 and its proximal end closed bythe plug 16. The inflating channel 21 and the drainage channel 22 arecontained within the main arm from the pointwhere the side arm 14 meetsthe main arm until channel 21 terminates in orifice 20 within theinflatable sleeve 19. On the side arm 14, between the plugged proximalend and the point where the side arm joins the main arm, an inflatedreservoir 17 is covered by and sealed against fluid loss by thespheroidal jacket 18 which compresses the reservoir longitudinally fromits normally prolate spheroidal shape to a more nearly spheroidal shapeor even to an oblate spheroidal shape. The compressed reservoir pressesagainst the jacket at each end to form pressure seals which prevent, orat least very much restrict, fluid loss from the jacket interior at theseals. In practice, the jacket is slipped over the proximal side arm endin place over the reservoir and the latter is inflated by a syringe orother fluid discharge means. The end seals are so effective that toobtain maximum inflation of the reservoir, it is desirable to vent thejacket as with the vent 23. Substantially selfclosing vents may be madein jackets of flexible material by piercing them from the outsideinwardly. This causes a hole with rather jagged edges to be produced andas the reservoir fills, the hole edges interfit to provide a substantialclosure. It is to be understood, however, that the jacket is effectivewhether a vent is or is not provided, or whether the vent hole isclosed.

In FIG. 2, the reservoir 17 on side arm 14 is uninflated and seals arenot yet formed with the jacket 18.

In FIG. 3, the reservoir 17 has been inflated sufficiently so that thereservoir ends are beginning to form seals against the jacket interior.As soon as the seal is effective, the vent 23 relieves the internalpressure between the reservoir and the jacket.

In FIG. 4, the reservoir 17 is fully inflated and the end seals whichprogressively increase in width as the reservoir is inflated meet nearthe equatorial circle of the jacket. The hole 23, if not substantiallyclosed is sealed around its edges by the inflated reservoir.

Vents made in jackets with a hot needle and whose bores take anhourglass configuration which measures at its widest point approximately0.012 inches' in diameter cause fluid losses only slightly greater thanunvented jackets. With fully inflated ll h cc. reservoirs at 70 F.maintained for 3 years, for instance, such a vent causes the jacket tolose only one-half cc. more fluid than an unvented jacket.

Preferably, the jackets of this invention are blow molded in one pieceof thermoplastic materials including glass. But they could be made ofmetal. Plastic materials can be injection molded in two pieces which canbe joined by any of several methods including solvent sealing,ultrasonic welding, heat sealing, cementing, etc. For the most part, thewall thickness should be upwards of 5 mils for most plastic jackets,somewhat less for glass jackets and at least 1 mil for metal jackets.The thickness obviously depends upon the strength and fluid transmissionrate of the materials used.

Suitable thermoplastic materials include polyethylene, polypropylene,polycarbonate, phenoxy resins and styrene blends such asstyrene-acrylonitrile resins. The latter three materials like glass arevery attractive because of their transparency. Obviously, materials withlow fluid transmission rates are to be preferred since they may be madeproportionately thinner.

1 While jackets with volumes in the range of 8 to 12 cc. are preferred,the size is optional and animal catheters and special hemostatic orpediatric catheters with larger or smaller retaining bulbs may requireproportionately larger or smaller reservoirs and corresponding jackets.

It has been postulated [Journal of Polymer Science l8z20l (1955) Berryand Watson] that stress relaxation of sulfur vulcanizates is essentiallythe result of first order degradation of more than one type ofcross-link. Our own tests with vulcanized latex tends to corroboratethese postulations. But regardless of the explanation of thedeterioration of the rubber latex,.the pressure within inflated rubberlatex reservoirs does deteriorate with time. If the known deteriorationin pressure continues fora sufficient period of time, it eventuallybecomes insuflicient to inflate the retention bulb. With an unprotectedaged reservoir, therefore, it may be necessary to squeeze the reservoirto inflate the retention bulb. I have discovered, however, that when thereservoir is inflated but not permitted to assume itsnatural inflatedcontours, the distorted inflated reservoir exerts a higher pressure uponthe same fluid contents than it does when it has its natural inflatedcontours. Not only is this initially true but it continues to be true asthe pressures in the distorted andnaturally contoured reservoirsdeteriorate with time. The jackets of this invention, therefore, so longas they are effective in distorting the reservoir, not only retain thefluid with minimal loss but also'retain the fluid at higher pressurethan otherwise. This insures that there will be sufficient liquid athigher. pressure for a longer period of time. For example, when observedwithin the range of temperatures'from F. to 120 F a coated catheterreservoir (A mil polyvinylidene chloride coating) loses waterapproximately 60 percent as fast as an uncoated catheter. A catheter ofthe invention (substantially spherical except at ends) loses waterapproximately l0 percent as fast as an uncoated catheter so long as thereservoir is effectively distorted.

Likewise, in the same observed temperature range, the jacketed reservoirof the invention, when inflated with the same amount of water as asimilar but unjacketed reservoir, initially exerts a greater pressure onthe contents which can be regulated by the relative size of the jacketbut reasonably is in the range of 2 to pounds per square inch greater.Until the jacket becomes ineffective due to loss of the end seals, thedifference in pressure, while reduced, continues to be significant.

The jacketed reservoirs of this invention need not be integral withcatheters. In some embodiments the reservoir assembly is detachableafter inflation of the inflatable retention means. In other embodimentsthe reservoir assembly is attached only during. inflation of theinflatable retention means. Connection may be accomplished by insertionof a hollow needle or by well known valvular means.

I claim:

1. ln' combination, a self-inflatable bag catheter comprising anelongated flexible thin-walled drainage tube open at its proximal endand having at least one lateral opening in its distal end, a thin-walledelastic sleeve adjacent the distal end of said drainage tube, saidsleeve being bonded along its marginal zones to the exterior surface ofsaid drainage tube to form a fluidtight seal along said marginal zonesof said sleeve and being unattached to said drainage tube along itscentral region whereby the central region of said sleeve is free toexpand laterally of said drainage tube upon the introduction of aninflating fluid into the space formed between the unattached centralregion of the sleeve and the exterior surface of the drainage tubeadjacent thereto, a flexible inflation tube opening at its distal endinto the space formed between the unattached central region of the saidsleeve and the exterior surface of the drainage tube adjacent thecentral region of the said sleeve, theflproximal end of said inflationtube terminating in an elastic 1n ation arm offset from the proximal endof sai drainage tube including a resilient inflated reservoir retaininga fluid under pressure, the natural shape of said reservoir whenunrestrained when inflated being prolate in which the axis thereof whichis parallel with the length of the inflation arm is the majorlongitudinalaxis, and a jacket enclosing the inflated reservoir, saidjacket restricting said inflated reservoir to a shape other than aprolate shape with its longitudinal axis parallel with the inflation armand restraining the inflated reservoir to a smaller longitudinaldimension than it would assume inflated with the same amount of fluidwhen unrestrained so that said axis of said reservoir which is parallelwith the length of the inflation arm is no greater than a major axisthereof perpendicular thereto and the amount of fluid in the restrainedand restricted shaped inflated reservoir being the same as the amount offluid in the reservoir inflated when unrestrained and unrestricted.

2. The catheter of claim 1 wherein a portion of the jacket interior isspheroidally concave.

3. The catheter of claim 1 wherein the interior of the jacket ispredominantly spherically concave in which all axes passing through thecenter thereof are substantially of equal length.

4. The catheter of claim 1 wherein the interior of the jacket ispredominantly oblately spheroidally concave in which the axis thereofparallel to the length of the inflation arm is shorter than anintersecting axis perpendicular thereto.

5. The catheter of claim 1 wherein the interior of the jacket ispredominantly prolately spheroidally concave in which its major axisintersects the longitudinal axis of the inflation arm and isperpendicular thereto.

6. The catheter of claim 1 wherein the interior surface of the jacket isin sealing contact with the exterior surface of the inflated reservoirthroughout substantially its entire surface area, the restrainedandrestricted shape of said inflated reservoir being such that upon partialloss of fluid from the reservoir and consequent deflation of thereservoir the total surface contact between the jacket and reservoir isgreater, for the same amount of fluid loss, than the total surfacecontact between a reservoir and enclosing jacket of a prolate shapecorresponding to the prolate shape the reservoir would have if inflatedwhen unrestrained.

1. In combination, a self-inflatable bag catheter comprising anelongated flexible thin-walled drainage tube open at its proximal endand having at least one lateral opening in its distal end, a thin-walledelastic sleeve adjacent the distal end of said drainage tube, saidsleeve being bonded along its marginal zones to the exterior surface ofsaid drainage tube to form a fluidtight seal along said marginal zonesof said sleeve and being unattached to said drainage tube along itscentral region whereby the central region of said sleeve is free toexpand laterally of said drainage tube upon the introduction of aninflating fluid into the space formed between the unattached centralregion of the sleeve and the exterior surface of the drainage tubeadjacent thereto, a flexible inflation tube opening at its distal endinto the space formed between the unattached central region of the saidsleeve and the exterior surface of the drainage tube adjacent thecentral region of the said sleeve, the proximal end of said inflationtube terminating in an elastic inflation arm offset from the proximalend of said drainage tube including a resilient inflated reservoirretaining a fluid under pressure, the natural shape of said reservoirwhen unrestrained when inflated being prolate in which the axis thereofwhich is parallel with the length of the inflation arm is the majorlongitudinal axis, and a jacket enclosing the inflated reservoir, saidjacket restricting said inflated reservoir to a shape other than aprolate shape with its longitudinal axis parallel with the inflation armand restraining the inflated reservoir to a smaller longitudinaldimension than it would assume inflated with the same amount of fluidwhen unrestrained so that said axis of said reservoir which is parallelwith the length of the inflation arm is no greater than a major axisthereof perpendicular thereto and the amount of fluid in the restrainedand restricted shaped inflated reservoir being the same as the amount offluid in the reservoir inflated when unrestrained and unrestricted. 2.The catheter of claim 1 wherein a portion of the jacket interior isspheroidally concave.
 3. The catheter of claim 1 wherein the interior ofthe jacket is predominantly spherically concave in which all axespassing through the center thereof are substantially of equal length. 4.The catheter of claim 1 wherein the interior of the jacket ispredominantly oblately spheroidally concave in which the axis thereofparallel to the length of the inflation arm is shorter than anintersecting axis perpendicular thereto.
 5. The catheter of claim 1wherein the interior of the jacket is predominantly prolatelyspheroidally concave in which its major axis intersects the longitudinalaxis of the inflation arm and is perpendicular thereto.
 6. The catheterof claim 1 wherein the interior surface of the jacket is in sealingcontact with the exterior surface of the inflated reservoir throughoutsubstantially its entire surface area, the restrained and restrictedshape of said inflated reservoir being such that upon partial loss offluid from the reservoir and consequent deflation of the reservoir thetotal surface contact between the jacket and reservoir is greater, forthe same amount of fluid loss, than the total surface contact between areservoir and enclosing jacket of a prolate shape corresponding to theprolate shApe the reservoir would have if inflated when unrestrained.